What is the deepest you have seated a bullet?

Cottis

Well-Known Member
I have reloaded lots of different bullets in different chamberings over a few years. Generally speaking, I tend to work out the max COAL for a given bullet in my actual rifle and ladder test with bullets seated 0.025" from the lands. Often that results in perfectly good enough accuracy but where it has not, increasing cartridge length has quickly realised stellar accuracy. I have never needed to jam bullets.

Fast forward to the last couple of weeks and I have been putting together a load to shoot the Barnes 62gn Varmint Grenades in 6mm.

I loaded up the usual 10 rounds or so to ladder test to find velocity plateaus and I then start testing for accuracy once I have chosen my charge weight. When testing charge weight velocities initially, rather than loading all cartridges 25 thou back from the lands, I loaded them all 0.050" shorter than max COAL inline with consensus with Barnes bullets in general. They evidently want a bigger jump than standard lead cored bullets. They aint wrong.

So I choose my charge weight and start putting together some cartridges for accuracy testing. 4 at 0.050", 4 at 0.075" and 4 at 0.100" off the lands. All 3 different seating depths shot like cack. Fair enough, so I go deeper. Same again but this time at 0.125", 0.150" and 0.175". Back to the field, shoot some groups and all are scattergun apart from the 0.175" which showed significantly better accuracy but still not what I would accept for the application i will be using it for. So i then load up the next batch at 0.200", 0.225" and 0.250" ha ha ha. At 0.250", it is on the limit of seeing a touch of daylight between the top lip of the neck and the bearing surface of the bullet shank. Still lots of bearing surface in contact with neck and neck tension fine but its looking a bit odd. These are long bullets given their weird lightweight powdered tin core, so there is a huge amount of bullet now inside the case. I go to the field and immediately 0.200" fires in under 3/4" and the next batch of 0.225" goes in to half an inch. The crazy deep 0.250" starts to show signs of opening up a bit in comparison but still an order of magnitude better than the initial earlier loads which grouped appallingly.

So, job done and load found but wow that is deep. I know certain bullets like a jump but this seems a touch mad but if it works, it aint crazy right?

Anyone else found mad behaviour with certain bullets?

I found very little information, at least for reach compliant powders, when trying to glean info on loading for this bullet. H380 was the apparent champion stateside, so i went with N140 and CCI BR2's and they certainly motor along. I found lots of info from people saying this bullet was basically no good and they could not get it to shoot. I wonder how many people try seating them super deep? Barnes clearly recommend trying to seat these deeper and deeper until you get results but this does seem extreme. Anyway, maybe this could help people if they wanted to find a non lead bullet that does actually expand and provide proper varmint like performance. It might save a few 6mm rifles that might end up being chopped in for a .224 when/if this stupid lead ban comes in.
 
The very very very deepest? When I loaded 7.62mm Nagant revolver ammunition. The bullet was fully inside the case with the case mouth past it.


With rifle ammunition for .303 always to factory OAL which given the tolerances on these things was likely some good way off the lands.

Some of the "all new" magnum rifles using the .300 H & H as a parent case in the 1960s they were actually made with a fair amount of what is called "freebore" at the lead into the barrel.

 
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They're good bullets. I've been using them a fair bit for roe in my 6x45. I don't think they're that far off the rifling in my rifle but I need to seat them deep to fit the mag.

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They're good bullets. I've been using them a fair bit for roe in my 6x45. I don't think they're that far off the rifling in my rifle but I need to seat them deep to fit the mag.

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They are long for weight aren't they? That is pretty deep in yours too.

But if they shoot, then it's all good. Mine are doing 3600fps in a 1 in 10 barrel. I expect the terminal results to be not pretty. I definitely will not be shooting anything I want to eat with this load but I would be interested to know how you find them at more pedestrian velocities.
 
They are long for weight aren't they? That is pretty deep in yours too.

But if they shoot, then it's all good. Mine are doing 3600fps in a 1 in 10 barrel. I expect the terminal results to be not pretty. I definitely will not be shooting anything I want to eat with this load but I would be interested to know how you find them at more pedestrian velocities.
I get about 3030 FPS with a full case (23gr) of N133. I'm sure a faster burning power would increase velocity.

I find the damage fairly substantial, especially at shorter ranges. I would say it's no better or worse than a 50gr TTSX from my 220 Swift at 3600 fps. Most of the time I get an exit, but occasionally find the part of the tin core in a carcass.

I'll try and take some photos of a carcass when I next get some with these bullets.

They're a nice shape and surprisingly long for the weight. They have a huge deep hollow point! A boat tail would be nice to increase the BC a bit, but can't really complain.
 
My 8mm Mauser has an enormous freebore so even when the bullets are seated as far out of the case as possible they still have a quarter inch jump to reach the lands. It's never going to be a match rifle because it kicks like a mule but it shoots ok - grouping between 1 and 2 MOA if I am doing my part.
 
Are you sure that it’s the seating depth that has improved the tHe group size? Reason I ask is that those depths are pretty extreme & the reduction in case volume for the same powder load will have a significant impact on pressure & hence velocity. Are you getting better groups because you’re driving the bullets faster? When I load test I stick to the same seating depth & try slight variations in powder weight; I then do the same again with the next seating depth & so on.
 
Are you sure that it’s the seating depth that has improved the tHe group size? Reason I ask is that those depths are pretty extreme & the reduction in case volume for the same powder load will have a significant impact on pressure & hence velocity. Are you getting better groups because you’re driving the bullets faster? When I load test I stick to the same seating depth & try slight variations in powder weight; I then do the same again with the next seating depth & so on.
It is never one thing is it? Something has to change to alter pressure, jump, barrel harmonics etc. I always feel like reloading is juggling variables and we are never in as much control as we would like to be.

I used to reload in a similar way to you but I found I was using lots of components and spending lots of time shooting targets when I needed to be shooting at other stuff. So after trying the traditional methods and then stuff like OCW, I did velocity strings via hyper accurate charge weighing and then chose a velocity plateau node and then stuck with it and altered seating depth, albeit very marginally in comparison to the insanity I am writing about with this Barnes bullet.

I would imagine that pressure and therefore velocity has risen by decreasing case volume so much. It simply has to as you suggest. It is effectively 0.175" deeper in the case than the initial chrono'd rounds. I was not recording velocity when shooting on paper though.

This rifle is a bit of an oddity in that it generates pressure/velocity much quicker than you would expect from this chambering. I have always know that it has either a tight chamber and/or bore. For example, this bullet was giving 3600fps @ 40.3gn of N140. I suspect the average .243 would need a significantly higher charge to reach that speed. With various other bullets, I have always found the case to be nowhere near as full as spec data or QL would suggest. I get 2880fps from a 100gn Prohunter for example with 37.50gns of N160 and it shoots unbelievably well.

So the case was not exactly full to start with but these bullets are seriously long for weight. That said, the loads are not close to being compressed and I have seen no pressure signs whatsoever. I will run the finished load back over the chrono to see what increase in velocity has resulted from this madness seating depth.

But yeah, no idea if it is seating depth, reduced case volume inceasing pressure/velocity or something else. It could even be a micro adjustment in terms of there being a touch less bearing surface of the ogive on the neck due to how deep it is seated.

I guess a bit like golf, I don't question the mechanics too much as long as it is not hurting my body. I let the ball be the teacher. Will update once I have run over the chrono.
 
Are you sure that it’s the seating depth that has improved the tHe group size? Reason I ask is that those depths are pretty extreme & the reduction in case volume for the same powder load will have a significant impact on pressure & hence velocity. Are you getting better groups because you’re driving the bullets faster? When I load test I stick to the same seating depth & try slight variations in powder weight; I then do the same again with the next seating depth & so on.
I shot a couple of rounds over the chrono just now (seated 0.225" off the lands whereas the initial velocity testing at different charge weights were seated 0.050" off the lands)

I was expecting maybe a slight increase in velocity but it has actually decreased from 3600fps to 3550fps. I mentioned before that this rifle develops pressure quicker than others at signicantly lower charge weights. This load has only 40.3gns of powder in it and I would normally expect to reach these velocities with at least a couple of grains more. I am guessing that allowed the deeper seating of the bullet to not realise any added pressure. To the point that moving the bullet so far away from the lands, allowed a drop in pressure which was then not fully offset by the decreased case capacity due to seating the bullet so deep.

Random. In any case, it is safe. It is quick enough but nowhere near the speeds supposedly attainable with other powders if the Barnes load data is to be believed. N140 is somewhere in the region of H380 and along with other powders suggested velocities went north of 3700fps. So it's accurate, its safe and it is totally weird and random but I guess I learn something new every day. What I don't know is why it suddenly started tightening up accuracy wise. Was it the crazy deep seating or was it actually the decrease in velocity it liked? Bit odd but all is well that ends well I guess.
 
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